Lock mechanism for drafting table



March 5, 1963 E. H. MAY 7 3,079,726

LOCK MECHANISM FOR DRAFTING TABLE Filed Feb. 17, 1961 2 sheets sheet 1March 5, 1963 E. H. MAY

LOCK MECHANISM FOR DRAFTING TABLE 2 Sheets-Sheet 2 Filed Feb. 1'7. 1961United States Patent ()filice 3&79325 Fatented Mar. 5, 1963 3,079,726LGCK MECHANISM FGR BRAFTENG TABLE Ellwood H. May, Sheboygan, Wis,assignor to Mayline Company, 1122., a corporation of Wisconsin FiiedFeb. 17, 1961, Ser. No. 89,953 11 Ciainis. (Cl. 45-131) This inventionrelates to novel and useful improvements in adjustable drafting tablesand particularly to a draft ing table having an improved apparatus forlocking the same in different adjusted positions.

An important object of this invention is to provide an adjustabledrafting table having an improved apparatus for locking the table in anyselected position and which permits smooth and substantially noiselessadjustment of the table between different positions.

Another object of this invention is to provide an ad justable draftingtable including a locking bar and a lock ing block slidable on the barand tiltable about its axis relative to the bar to lock the table inadjusted position, and which locking block is mounted in a manner tominimize wear and abrasion on the bar and block as they slide relativeto each other during adjustment of the table.

A more particular object of this invention is to provide an adjustabledrafting table in accordance with the foregoing object in which thelocking block is mounted for free floating movement in a directiontransverse to the direction of relative movement between the bar and theblock to accommodate irregularities in the bar and to prevent rubbing orbinding of the block on the bar during adjustment of the table.

Another object of this invention is to provide a locking mechanism forlocking a drafting table in an adjusted position, and which lockingmechanism is of simple and economical construction and which is reliablein operation.

These, together with various ancillary objects and advantages of thisinvention will be more readily appreciated as the same becomes betterunderstood by reference to the following detailed description when takenin connection with the accompanying drawings wherein:

FIGURE 1 is a fragmentary side elevational view of a drafting table withthe side panel removed and illustrating the adjustable support for thetable;

FIG. 2 is an enlarged fragmentary horizontal sectional view taken on theplane 2-.?. of FIG. 1 and illustrating the locking mechanism in itsreleased position;

FIG. 3 is a fragmentary transverse sectional view taken on the plane 33of FIG. 2;

FIG. 4 is a fragmentary vertical sectional view illustrating a modifiedform of locking apparatus;

FIG. 5 is a fragmentary vertical sectional view taken on the plane 55 ofFIG. 4;

FIG. 6 is a horizontal sectional view taken on the plane 65 of FIG. 5;

FIG. 7 is a horizontal sectional view illustrating a further modifiedform of locldng apparatus; and

FIG. 8 is a fragmentary horizontal sectional view illustrating stillanother form of locking apparatus.

The present application is a continuation-in-part of my copendingapplication for Adjustable Support for Drafting Table, Serial No.767,713, filed October 16, 1958, now Patent No. 2,982,050. As disclosedin the aforementioned application, the drafting table includes a supportbase 16 having side frame members 11 adjacent opposite sides thereof andcrosspieces 12 extending between the side frame members to interconnectthe same. In the drafting table illustrated, a fixed table top 13 ismounted to extend between the side members. A drafting board 14 ismounted on the base for vertical adjustment with respect thereto andalso for limited lateral tilting movement. As shown, the drafting boardis mounted for vertical adjustment by means of a pair of link members 13and 19 which are pivotally attached at 21 and 22 to a respective one ofthe side members 11. The links are supported for swinging movement in avertical plane and an upright member or post 24 is pivotally connectedto the other side of the links 18 and 19, as by pivot pins 25 and 26, toform a parallelogram-type linkage. The post advantageously comprises tworelatively adjustable sections 28 and 29 which are adjustably securedtogether by fasteners 31 to enable stepped adjustment of the elevationof the drafting board.

The drafting board 14 is mounted on the upright memher or post 24 forswinging movement about a horizontal axis and, as shown, the draftingboard has bracket members 33 secured to rails 34 on the underside of thedrafting board, and which bracket members are pivotally mounted by pins35 to the post 24 to support the drafting board for lateral tiltingmovement. As more fully disclosed and claimed in the aforementionedapplication, a spring type counterbalance is provided to facilitateelevating and lowering of the board. In general, the spring 38 isadjustably connected at its upper end 39 to the respective side member11. The lower end of the spring 38 is connected to an arm 42 whichextends laterally of the link 19. The point of attachment of the spring38 to the arm 42 is spaced an appreciable distance below thelongitudinal axis of the link 19 whereby the point at which the springcrosses the lower link can shift away from the pivot axis 22 of thelower link as the link swings upwardly to thereby increase the effectivedistance be tween the spring and the pivot point of the lower link.Thus, while the force or tension exerted by the spring 38 increases asthe link 19 swings upwardly, the effective distance between the spring33 and the pivot point of the lower link is increased so as to therebycompensate for the decrease in spring tension and to maintain asubstantially uniform lift on the drafting board.

In accordance with the present invention, an improved locking apparatus51 is provided for adjustably locking the drafting board in apreselected elevated position and a similar locking apparatus designatedgenerally by the numeral 52 is provided for locking the drafting boardin a preselected inclined position. In the embodiment illustrated, thelocking mechanism 51 includes a locking bar 55 which is pivotallymounted at 56 to the upper link member 18. A locking block 57 is mountedon the side frame member 3'11 and is tiltable relative to the rod tolock the rod and the drafting board 14 in a preselected verticallyadjusted position. The locking mechanism 52 also includes a locking bardesignated 58 and, as shown, the

locking bar 58 is in the form of a semi-circle and has table.

. a turning the locking block 62 into its locked position, and amanually operable release lever 66 is provided for selectively movingthe locking block 62 to its released position.

The construction and mounting of the locking block 57 for locking thedrafting board in a vertically adjusted position is the same as thatemployed in constructing and mounting the locking block 6'2 which looksthe drafting table in an inclined position and accordingly theconstruction and mounting of only one of the locking blocks designated57 is herein illustrated and described in detail. As shown in FIGS. 2and 3, the locking block 57 is mounted for rotation on a shaft 75 whichextends crosswise between the side frame members 11 and has sleeves 76at the ends thereof. Each sleeve 76 is rotatably supported in an openingor bearing 77 in the side frame member 11 and is constrained againstaxial movement by a collar 78 secured to the sleeve by a set screw 79.The sleeve has a diametrically extending slot 81 which opens at the endof the'sleeve opposite the shaft 75 and which slidably receives theelongated generally flat locking block 57. The locking block is thussupported for rotation with the shaft 75, with'the axis of the blocksubstantially aligned with the axis-of the shaft, and a spring 83 isattached to the outer end of arod 84 connected to'the shaft to yieldablyturn the shaft in one direction into a locked position. A manual releaselever, herein shown in the form of a foot treadle 86, is attached to theshaft for selectively turning the same in a relatively oppositedirection to its released position. v I

As best shown in FIG. 2, the block 57 has an enlarged opening 88 thereinhaving a diameter larger than the rod SSand'Which slidably receives thesame. Recesses 8? are advantageously formed at diametrically'opposedsides of the opening 88 and have a width less than the diameter of theopening to form opposed pairs of cusps'or' points 91 which are arrangedto engage the rod 55 when the block is tilted to lock the rod againstrelative movement.

In order to accommodate irregularities in the locking bar 55'andin; therelative spacing between the bar and the sleeve as the link membersareraised and lowered. relative'to'the side frame members, provision ismade for mounting the locking block 57 for free floating movement in adirection axially and crqsswise of the sleeve; In the form shown inFIGS. 2,and,3, a pin 93 is attached to the sleeve 76 and extendscrosswise of the slot 81 therein and through a relatively enlargedopening 94 in the locking block. The pin retains the locking blockagainst accidental dislodgement from the slot and suflicient clearanceis provided between the pin and the opening 94 in the block to permitlimited axialand, crosswise floating movement of the locking blockrelative to the sleeve and shaft. The block 57, at least in that portionwhich extends through the ring 78 and through bearing or opening 77 inthe side frame member 11 is dimensioned narrower than the. outerdiameter of the sleeve 76 so that the collar andsideframe, members donot inhibit crosswise shifting oftheb lock. The locking block istherefore free to align itself-with the bar 55 as the block and bar. aremoved relative to each other so as to .minimizewear and abrasion .aswell as noise during adjustment .of the drafting In addition, when theshaft 75 is turned about its axis, and thereby tilts the locking block57, the locking block can also shift sufiicient'to allow all four of thecusps 91 to substantially uniformly engage the bar 55 to lock the partsagainst relative movement. This floating movement of the locking blocktherefore allows the block to align itself with the bar to avoid wearduring adjustmentand to alsoprovidemore reliable locking of the Vrelatively movable parts.

A somewhat modified form -of locking mechanism is il' lustrated in FIGS.4-6. This locking mechanism is generally similar to that shown in FIGS.2 and 3 and like numerals followed by; the, sub-script a areutiIiZeditQ; designate corresponding parts. The embodiment of FIGS.

4-6 also includes a shaft a having a sleeve 76a at one end rotatablysupported in the side frame member 11a. The shaft is yieldably turned inone direction by means of a spring 83:: and rod 84a and the sleeve has aslot 81a therein which opens at the end of the sleeve and which slidablysupports the locking block 57a. A collar 78a is secured to the sleeveand abuts against the side mem ber 11a to limit axial movement of theshaft relative to the side member. The locking block has an enlargedopening 88a which loosely receives the bar 55a and which opening hasdiametrically opposed recesses 89a defining opposed pairs of cusps 91a.

The locking block 57a is supported for free floating movement in adirection axially and crosswise of the shaft within the slot 81a and isconstrained. against axial detachment from the slot by means of agenerally U- shaped pin 93a. The pin 93a straddles the sleeve 76a andhas leg'portions thereof disposed in notches a in the sleeve. The legportions extend crosswise of the slot 81a in the sleeve, adjacentopposite side edges thereof, and notches or openings 94a are formed inopposite side edges of the locking block 57a. As shown in FIG. 6, thenotches 94a loosely receive the legs of'the pins 93a so that the lockingblock can float axially as well as crosswise of the sleeve as requiredfor alignment with the bar. 55a. The locking block, at least in. theportion thereofextending through the opening 77:: andthe collar 78a, isdimensioned narrower than the opening so that the collarand side member11 do not inhibit lateralfloating movement of the locking block.

A further modified arrangement for retaining the locking block in thesleeve, while permitting free axial and crosswise floating thereof, isillustrated in FIG. 7. In this embodiment, the sleeve 76b is attached tothe shaft 75b and has a collar 78b thereon for limiting axial movementof the sleeve relative to the side frame member 11b. The generally fiatlocking block 57b is also slidably disposed in a slot designated 81b inthe-sleeve and a second collar 95b is disposed around the sleeveintermediate theends of the slot. The collar has threaded'pins'93bthereon which project into. the/slot 81b and into openings or. notches94b in opposite side edges of the locking block. As in'the previousembodiments, the locking block 57b has a width less than the outerdiameter of the sleeve to permit lateral floating movement of thelocking block, and the notches 94b loosely receive the pins 93b topermit axial-and crosswiseshifting of the locking block relative to thelocking bar 55b.

In certain applications, the locking bar'can be utilized to retain thelocking block against dislodgement from the slot in the sleeve, so thathis not necessary to provide a separate means for preventing axialdislodgement of the locking block. Thus, the bar can be secured atopposite ends in the same manner as the arcu'ate bar 58,"shown in FIG.1; With'this arrangement, there maybe minor variations-in the relativespacing between the locking bar and the shaft due to irregularities inthe'bar'as the locking block slidesalong the 'bar; However, thevariationsare not suflicient to permit dislodgement of the block fromthe sleeve. Similarly, the straight bar such as 55in FIG.

1 can be mounted so that it does not swing appreciably in a directionlongitudinally of the locking shaft. In this event, the locking blockdesignated need only be con strained against latenal movementout of theslot. 7 As shown in embodiment of FIG. 8, a tongue 930 is provided onthe end of theloeking block57c which tongue the block 570 is alsosupported for limited axial andcrosswise shifting relative to the sleeve76c and shaft 750.

Fromqthe foregoing, it is apparent that the locking blocks are mountedfor turning movement with the respective shaft to thereby tilt relativeto the respective "locking bar and lock thereagainst. The lockingblocks,

however, are supported for free axial and lateral shifting movementrelative to the respective shaft so as to accommodate variations in thespacing between the shaft and the bar, as the locking block and barslide relative to each fother, and to also facilitate shifting of thelocking block during the locking operation so that the cusps on thelocking block substantially uniformly engage the bar.

I claim:

1. In combination with a drafting table including a drawing board, firstand second relatively movable members for adjustably supporting saidboard, means for locking said board in selectively adjusted positionscomprising, a rod attached to said first member, bearing means on saidsecond member, shaft means rotatably mounted in said bearing means onsaid second member for rotation about an axis transverse to said rod, alocking block having an opening loosely receiving said rod and operativewhen tilted relative to the rod to bind thereagainst and lock the rodand block against relative movement, means mounting said locking blockon said shaft means in substantial alignment with the axis of the shaftmeans for turning movement therewith and for limited movement relativeto the shaft means in a direction axially and crosswise of the shaftmeans [0 accommodate variations in the relative spacing between the rodand shaft means as said first and second members move relative to eachother, means yieldably turning said shaft means in one direction aboutits axis to normally tilt the block relative to the rod and lock themembers against relative movement, and manually operable means forselectively turning the shaft means in the opposite direction to releasethe rod.

2. In combination with a drafting table including a drawing board, firstand second relatively movable members for adjustably supporting saidboard, means for locking said board in selectively adjusted positionscomprising, a rod attached to said first member, bearing means on saidsecond member, shaft means rotatably mounted in said bearing means onsaid second member for rotation about an axis transverse to said rod,said shaft means having a transverse slot at the end thereof adjacentsaid rod, a locking block having one end portion thereof slidably andnon-rotatably disposed in said slot and having an opening thereinloosely receiving said rod, means including said slot mounting saidblock on the shaft means for limited sliding movement relative to theshaft means in a direction axially and crosswise of the latter toaccommodate variations in the relative spacing between said rod andshaft means as said first and second members move relative to eachother, means yieldably turning said shaft means in one direction aboutits axis to normally tilt the block relative to the rod and lock saidmembers against relative movement, and manually operable means forselectively turning said shaft means in the opposite direction torelease said rod.

3. The combination of claim 2 wherein said block mounting means includesa pin mounted on said shaft means extending transverse to said slot,said locking block having an opening in said one end portion dimensionedlarger than said piri to loosely receive the pin whereby to retain theblock in the slot While permitting limited axial and crosswise movementof the block relative to the shaft means.

4. The combination of claim 2 wherein said block mounting means includesspaced pins mounted on said shaft and extending into said slot adjacentopposite side edges thereof, said block having openings in said one endportion at opposite side edges thereof dimensioned larger than said pinsto loosely receive the pins whereby to retain the block in the slotwhile permitting limited axial and crosswise movement of the blockrelative to the shaft means.

5. The combination of claim 2 wherein said shaft means has notches inopposite side edges thereof intersecting said slot, said shaft mountingmeans including a U-shaped clip having spaced leg portions defining pinsextending through said notches and crosswise of said slot adjacentopposite side edges of the latter, said block having openings in saidone end portion at opposite side edges thereof dimensioned larger thansaid pins to loosely receive the pins whereby to retain the block in theslot While permitting limited axial and crosswise movement of the blockrelative to the shaft means.

6. The combination of claim 2 wherein said shaft mounting means includesa ring extending around said shaft means intermediate the ends of saidslot, said block having a width at adjacent said ring which is narrowerthan said ring.

7. The combination of claim 6 including a pin attached to said ring andextending into said slot, said block having an opening in the side edgethereof dimensioned larger than said pin to loosely receive the latter.

8. In combination with a drafting table including a drawing board, firstand second relatively movable members for adjustably supporting saidboard, means for locking said board in adjusted position comprising, arod attached to said first member, heating means on said second member,shaft means rotatably mounted in said bearing means on said secondmember for rotation about an axis transverse to said rod, said shaftmeans including a sleeve portion on the end thereof, said sleeve portionhaving a transverse slot in the end thereof adjacent said rod, a lockingblock slidably and non-rotatably disposed in said slot and having anopening therein loosely receiving said rod, means including said slotloosely mounting said block on the shaft means for limited slidingmovement relative to the sleeve portion in a direction axially andcrosswise of the sleeve portion to accommodate variations in therelative positions of said rod and shaft means as said first and secondmembers move relative to each other, means yieldably turning said shaftmeans in one direction about its axis to normally tilt the blockrelative to the rod and lock said members against relative movement, andmanually operable means for selectively turning said shaft means, in theopposite direction to release the rod.

9. The combination of claim 8 wherein said block mounting means includesa tongue on the end of said block remote from said opening therein andprojecting into said sleeve portion beyond the slot, said tongue toretain said bolck in the slot while permitting limited axial andcrosswise shifting movement of the block relative to the sleeve portion.

10. In combination with a drafting table including a drawing board,first and second relatively movable members for adjustably supportingsaid board, means for locking said board in selectively adjustedpositions com prising, a rod having a round cross-section attached tosaid first member, bearing means on said second member, shaft meansrotatably mounted in said bearing means for rotation about an axistransverse to said rod, a locking block having an opening thereinloosely receiving said rod, said opening including a generally circularhole di mensioned larger than said rod to loosely receive the same and apair of diametrically opposed recesses having a width less than saidhole and intersecting the same to define opposed pairs of cuspsengageable with the rod, to bind thereagainst when the block is tiltedrelative to the rod, means mounting said locking block on said shaftmeans in substantial alignment with the axis of the shaft means forturning movement therewith and for limited movement relative to theshaft means in a direction axially and crosswise of the shaft means toaccommodate variations in the relative spacing between the rod and shaftmeans as said first and second members move relative to each other,means yieldably turning said shaft means in one direction about its axisto normally tilt the block relative to the rod and lock the membersagainst relative movement, and manually operable means for selectivelymam 7 V 8 v turning the shaft means in the opposite direction to releaselock the same against movement when theblock is tilted the rod. 7relative to the rod.

11. The combination of claim 1 wherein said opening in said block isdefined by an enlarged circular hole for References Cited in the file Ofthis Patent loosely receiving said rod and a pair of diametrically op- 5UNITED STATES PATENTS posed recesses intersecting said hole at oppositesides of the axis of the shaft means and having a width at the 2,FrOeliCh Aug. 29,1944 intersection with said hole which is less than thediameter 2,833,081 Pottern May 6, 1958 of said hole to define cuspsengageable with said rod to ,92 ,299 Kanzelberger t a1 9. 1950

1. IN COMBINATION WITH A DRAFTING TABLE INCLUDING A DRAWING BOARD, FIRSTAND SECOND RELATIVELY MOVABLE MEMBERS FOR ADJUSTABLY SUPPORTING SAIDBOARD, MEANS FOR LOCKING SAID BOARD IN SELECTIVELY ADJUSTED POSITIONSCOMPRISING, A ROD ATTACHED TO SAID FIRST MEMBER, BEARING MEANS ON SAIDSECOND MEMBER, SHAFT MEANS ROTATABLY MOUNTED IN SAID BEARING MEANS ONSAID SECOND MEMBER FOR ROTATION ABOUT AN AXIS TRANSVERSE TO SAID ROD, ALOCKING BLOCK HAVING AN OPENING LOOSELY RECEIVING SAID ROD AND OPERATIVEWHEN TILTED RELATIVE TO THE ROD TO BIND THEREAGAINST AND LOCK THE RODAND BLOCK AGAINST RELATIVE MOVEMENT, MEANS MOUNTING SAID LOCKING BLOCKON SAID SHAFT MEANS IN SUBSTANTIAL ALIGNMENT WITH THE AXIS OF THE SHAFTMEANS FOR TURNING MOVEMENT THEREWITH AND FOR LIMITED MOVEMENT RELATIVETO THE SHAFT MEANS IN A DIRECTION AXIALLY AND CROSSWISE OF THE SHAFTMEANS TO ACCOMMODATE VARIATIONS IN THE RELATIVE SPACING BETWEEN THE RODAND SHAFT MEANS AS SAID FIRST AND SECOND MEMBERS MOVE RELATIVE TO EACHOTHER, MEANS YIELDABLY TURNING SAID SHAFT MEANS IN ONE DIRECTION ABOUTITS AXIS TO NORMALLY TILT THE BLOCK RELATIVE TO THE ROD AND LOCK THEMEMBERS AGAINST RELATIVE MOVEMENT, AND MANUALLY OPERABLE MEANS FORSELECTIVELY TURNING THE SHAFT MEANS IN THE OPPOSITE DIRECTION TO RELEASETHE ROD.